The value of cotton (Gossypium hirsutum cv. Deltapine 90) in rotation with peanut (Arachis hypogaea cv. Florunner) for the management of root-knot nematode (Meloidogyne arenaria) and southern blight (Sclerotium rolfsii) was studied for 6 years in a field at the Wiregrass Substation in southeast Alabama. Peanut yields following either 1 or 2 years of cotton (C-P and C-C-P, respectively) were higher than those of peanut monoculture without nematicide [P(-)]. At-plant application of aldicarb to continuous peanut [P(+)] averaged 22.1% higher yields than those for P(-) over the 6 years of the study. The use of aldicarb in cotton and peanut in the C-C-P rotations increased yields of both crops over the same rotations without the nematicide. When the nematicide was applied to both crops in the C-P rotation, peanut yields were increased in only two of the possible three years when peanut was planted. Application of aldicarb to cotton only in the C-P rotation did not improve peanut yields over those obtained with the rotation without nematicide. Juvenile populations of M. arenaria determined at peanut-harvest time were lowest in plots with cotton. Plots with C-P or C-C-P had lower populations of the nematode than those with either P(-) or P(+). The incidence of southern blight (Sclerotium rolfsii) in peanut was lower in plots with the rotations than in those with peanut monoculture. Aldicarb application had no effect on the occurrence of southern blight.
chemical control; crop rotation; Meloidogyne arenaria; nematicide; nematode; pest management; root-knot nematode; Sclerotium rolfsii; southern blight
The relationship between root stunting caused by the cereal cyst nematode and levels of two root growth inhibiting hormones, abscisic acid and ethylene, was investigated in aseptically cultured root segments and in intact roots of two oat cultivars differing in tolerance to the nematode. Cultured root segments of oat cultivars New Zealand Cape (tolerant) and Sual (intolerant) were inoculated with sterilized Heterodera avenae second-stage juveniles. Suppressed growth of root axes and emerged laterals following nematode penetration corresponded to an increase in abscisic acid and ethylene in roots of both intolerant and tolerant cultivars. When the experiment was repeated on intact root systems, nematodes retarded root growth of Sual more than New Zealand Cape despite an increase in ABA and ethylene in both cultivars. Abscisic acid and (or) ethylene may be involved in growth inhibition of H. avenae-infected roots but appear to play no direct role in determining tolerance.
abscisic acid; Avena sativa; axenic culture; cereal tryst nematode; ethylene; Heterodera avenae; nematode; oat; plant hormone; root elongation; root explant; tolerance
Ditylenchus dipsaci (Kühn) Filipjev is a serious pest of commercial daffodil (Narcissus sp.) in northern California. The control measures practiced by growers in recent years are postharvest treatment of planting bulbs for 3 hours in a 1% solution of formalin at 44 C combined with preplant soil fumigation with 1,3-dicbloropropene and (or) at-planting applications of phorate. In field trials, several combinations of rates (1.12, 2.24, or 4.48 kg a.i./ha in 189 liters of water/ha) and timings (one, two, or three applications at weekly intervals) of foliar applications with oxamyl on three daffodil varieties (Fortune, Ice Folley, and King Alfred) were evaluated as alternatives. Several treatments reduced nematode levels in leaves and bulbs. Phytotoxicity was not observed at any rate or combination of treatments.
chemical control; daffodil; Ditylenchus dipsaci; foliar application; Narcissus sp.; nematicide; nematode; nonfumigant nematicide; oxamyl; stem and bulb nematode
The efficacy of controlling Meloidogyne hapla on potato with water incorporation of ethoprop was compared to physical incorporation before planting. The standard practice of aldicarb application for insect control was also evaluated for M. hapla suppression with and without ethoprop. Physical incorporation before planting by rototilling or discing reduced (P ≤ 0.05) tuber infection. Postplant water incorporation of ethoprop was not as effective as physical incorporation of ethoprop or postplant water incorporation of aldicarb and did not reduce (P ≤ 0.05) tuber infection at harvest. Ethoprop did not affect yield, whereas aldicarb increased yield in one experiment.
aldicarb; chemical control; ethoprop; incorporation method; Meloidogyne hapla; nematicide; nematode; northern root-knot nematode; potato; Solanum tuberosum
Because the race scheme for Heterodera glycines was expanded recently from 5 to 16 races, the occurrence and distribution of races in Illinois need clarification. Forty-four populations of H. glycines were collected from sites in 23 of the 88 infested counties. Populations were tested using the differential soybean lines Pickett 71, Peking, PI 88788, and PI 90763. Lee 68 and Williams 82 were used as standards. Seedlings were grown in 7.5-cm-d clay pots and inoculated with 1,000 eggs and second-stage juveniles obtained from H. glycines-infested field soil. Plants were maintained in a greenhouse at 22-28 C. After 1 month, the number of first-generation white females that developed on each differential was determined and the race of the population was designated. Twenty-eight populations were race 3, twelve were race 1, two were race 5, one was race 2, and one was race 4. Populations of races 3 and 1 were widely distributed in the state. In 26 of the 28 race determinations, race designations using Williams 82 and Lee 68 were the same, indicating that if Lee 68 is not available, Williams 82 may be a suitable alternative for race tests done in the north central United States.
distribution; Glycine max; Heterodera glycines; nematode race; soybean cyst nematode
Hemicycliophora ritteri and Paratrichodorus minor were associated in high numbers with a previously unknown "dieback disease" of cranberry. Chemical treatment with nematicides and fungicides failed to control this disease. There were no correlations (P ≤ 0.05) among nematode numbers and yields of good or rotten berries, and with disease ratings. Nematodes were apparently not involved in the etiology of this dieback disease.
cranberry; cranberry dieback; Hemicycliophora ritteri; nematode; Paratrichodorus minor; Vaccinium macrocarpon
Responses of egg masses, free eggs, and second-stage juveniles (J2) ofMeloidogyne hapla and M. chitwoodi to ethoprop were evaluated. The results indicated that J2 were the most sensitive, followed by free eggs and egg masses. In general, M. chitwoodi was more susceptible to ethoprop than M. hapla. Ethoprop at 7.2 μg a.i./g soil protected tomato roots from upward migrating M. chitwoodi for 5 weeks. The zone of protection was extended to 10 and 20 cm below the root zone when 3.6 and 7.2 cm water were applied over 8 days. Ethoprop at 1.8, 3.6, and 7.2 μg a.i./g soil degraded faster and killed fewer M. chitwoodi J2 in potato field soil previously exposed to ethoprop than in unexposed soil or sterilized exposed soil. The enhanced biodegradation property of the exposed soil lasted 17 months after the last application of ethoprop. The limited downward movement of ethoprop in the soil, migration of M. chitwoodi J2 into the treated zone, presence of resistant life stage(s) at the time of application, and loss of efficacy due to enhanced biodegradation may have a significant effect on the performance of ethoprop.
biodegradation; Columbia root-knot nematode; ethoprop; Meloidogyne chitwoodi; Meloidogyne hapla; migration; nematicide; nematode; northern root-knot nematode; potato; Solanum tuberosum
A method for the cryopreservation of third-stage infective juveniles (IJ) of Steinernema carpocapsae and Heterorhabiditis bacteriophora was developed. Cryoprotection was achieved by incubating the nematodes in 22% glycerol (S. carpocapsae) or 14% glycerol (H. bacteriophora) for 24 hours, followed by 70% methanol at 0 C for 10 minutes. The viability of S. carpocapsae frozen in liquid nitrogen as 20 μl volumes spread over cover slip glass was > 80%. Survival of H. bacteriophora frozen on glass varied from 10 to 60% but was improved to > 80% by replacing the glass with filter paper. Cryopreservation and storage of 1-ml aliqots of S. carpocapsae IJ resulted in > 50% survival after 8 months; pathogenicity was retained and normal in vitro development took place. Trehalose and glycerol levels increased and glycogen levels decreased during incubation of S. carpocapsae IJ in glycerol. Normal levels of trehalose, glycerol and glycogen were restored during post freezing rehydration.
cryopreservation; desiccation; entomopathogenic nematode; Heterorhabditis bacteriophora; nematode; Steinernema carpocapsae
Two temperate corn (Zea mays) hybrids (Pioneer 3320 and Northrup King 508), two tropical corn cultivars (Pioneer X304C hybrid and Florida SYN-1 experimental open pollinated cultivar), the sorghum (Sorghum bicolor) x sudangrass (Sorghum sudanense) hybrid DeKalb SX-17, and the sorghum hybrid DeKalb FS25E were compared for effect on nematode densities and forage yield in three plantings (one single-crop and one double-crop system) in Florida. Final population densities of Meloidogyne incognita in the three plantings ranged from 0 to 13/100 cm³ soil on the two Sorghum spp. and were lower (P ≤ 0.001) than those obtained on the corn cultivars (range 147 to 762/100 cm³ soil). Early planted temperate corn and sorghum generally gave higher forage yields than did tropical corn. As second crops in double-cropping systems, tropical corn cultivars generally produced greater yields than temperate corn hybrids did. At 35% dry matter, double crop forage corn yield ranged from 51.1 to 64.8 ton/ha, and sorghum ranged from 79.8 to 102.2 ton/ ha. Tropical corn, forage sorghum, and sorghum-sudangrass were profitably grown at all planting dates. Late summer planting of temperate corn was unprofitable. DeKalb SX-17 sorghum x sudangrass first crop plus the ratoon double crop gave the highest net return of $1,133/ha. Among the corn cultivars, Florida SYN-1 gave the highest double crop net return of $652/ha.
corn; Criconemella ornata; Criconemella sphaerocephala; cropping systems; double cropping; Meloidogyne incognita; nematode; Paratrichodorus minor; Pratylenchus scribneri; Sorghum bicolor; sorghum-sudangrass; Zea mays
A Pratylenchus neglectus population from lltah (UT3) was more virulent to Lahontan alfalfa than other P. neglectus populations from Utah (UT1, UT2) and Wyoming (WY). All alfalfa plants survived at 24 ± 3 C when inoculated with WY, UT1, or UT2 at initial populations (Pi) of 500, 1,000, and 5,000 nematodes per plant. At Pi 10,000 with WY, UT1, or UT2, plant mortality was 15, 15, and 20%, respectively; at Pi 5,000 and 10,000 with UT3, plant mortality was 10 and 40%. The WY, UT1, and UT2 populations reduced (P ≤ 0.05) root growth at Pi 10,000 only, and UT3 reduced (P ≤ 0.05) root growth at Pi 1,000, 5,000, and 10,000. At Pi 5,000, shoot dry weights were reduced by 10-23% by WY, 14-29% by UT1, 12-25% by UT2, and 20-48% by UT3 at 15-30 C. The UT3 population reduced (P ≤ 0.05) root dry weight at 20-30 C at Pi 1,000 and 5,000. The WY, UT1, and UT-2 populations did not reduce (P ≥ 0.05) root growth at any temperature or Pi. The UT3 nematode reproductive indices were greater than those of the other nematode populations at all Pi and increased with temperature.
alfalfa; Lahontan; Medicago sativa; nematode; plant survival; Pratylenchus neglectus; reproduction; temperature; virulence
Meloidogyne incognita race 1, M. javanica, M. arenaria race 1, M. hapla, and an undescribed Meloidogyne sp. were analyzed by comparing isozyme phenotypes of esterase, malate dehydrogenase, phosphoglucomutase, isocitrate dehydrogenase, and α-glycerophosphate dehydrogenase. Isozyme phenotypes were obtained from single mature females by isoelectric focusing electrophoresis. Of these five isozymes, only esterase and phosphoglucomutase could be used to separate all five Meloidogyne spp.; however, the single esterase electromorphs were similar for M. incognita and M. hapla. Yet when both nematodes were run on the same gel, differences in their esterase phenotypes were detectable. Isozyme phenotypes from the other three isozymes revealed a great deal of similarity among M. incognita, M. javanica, M. arenaria, and the undescribed Meloidogyne sp.
biochemical systematics; electrophoresis; enzyme; esterase; α-glycerophosphate dehydrogenase; isocitrate dehydrogenase; isoelectric focusing; malate dehydrogenase; Meloidogyne arenaria; M. hapla; M. incognita; M. javanica; nematode; phosphoglucomutase
Methods were developed for screening Prunus selections for host suitability to Criconemella xenoplax. The relative host suitability of selections was based upon a doubling accumulation value (β) that was defined as the number of degree-days (base 9 C) required for doubling of an increment of the initial nematode population. The β value characteristic for C. xenoplax (139 ± 8 degree-days) on suitable hosts was similar to the average β value determined for several peach rootstocks known to be suitable hosts. The β values were 144 ± 21 for Halford, 141 ± 16 for Lovell, and 138 ± 10 for Nemaguard. A higher value for β could indicate poorer host suitability or resistance of a selection to C. xenoplax. All of 369 Prunus accessions tested, including eight accessions that had survived well on a field site infested with C. xenoplax, were suitable hosts. Apparently, resistance to C. xenoplax was not a factor in survival of the accessions planted in the field. Seedlings from P. besseyi, P. pumila 'Mando', and two interspecific hybrids, Redcoat and Sapalta IR 549-1, failed to support nematode population increase in 44-81% of tests conducted, but all selections supported population increase in some tests. These accessions may have resistance mechanisms that are active only under specific conditions.
carrying capacity; Criconemella xenoplax; degree-day; host suitability; Mesocriconema xenoplax; modelling; nematode; peach; population increase; Prunus; resistance
A new aseptic culture system for studying interactions between tomato (Lycopersicon esculentum) and Meloidogyne incognita is described. Epidermal thin cell layer explants from peduncles of tomato produced up to 20 adventitious roots per culture in 4-9 days on Murashige &Scoog medium plus kinetin and indole acetic acid. Rooted cultures were transferred to Gamborg's B-5 medium and inoculated with infective second-stage juveniles. Gall formation was apparent 5 days after inoculation and egg production by mature females occurred within 25 days at 25 C in the susceptible genotypes Rutgers and Red Alert. Resistant genotypes LA655, LA656, and LA1022 exhibited a characteristic hypersensitive response. This system provides large numbers of cultured root tips for studies on the molecular basis of the host-parasite relationship.
aseptic culture; host resistance; host susceptibility; Lycopersicon esculentum; Meloidogyne incognita; nematode; southern root-knot nematode; tomato
The host efficiencies of corn, sorghum, soybean, and wheat were compared for a Kansas population of Belonolaimus sp. under greenhouse conditions. In a related field study conducted in 1989 and 1990, the responses of Belonolaimus sp. and Pratylenchus scribneri populations to eight cropping regimes were monitored at depths of 0-30 and 31-60 cm in sandy soil. With the exception of alfalfa, all crop species examined supported substantial increases in populations of both nematodes. Largest nematode population increases in the field occurred in corn plots, whereas alfalfa did not allow reproduction by either species during the 2 years of observation. Soil populations of both nematodes remained at detectable levels after 2 years of fallow. The distribution of numbers of Belonolaimus sp. between soil depths varied with sampling date, whereas populations of P. scribneri were consistently concentrated in the top 30 cm of soil.
alfalfa; Belonolaimus sp.; corn; crop rotation; fallow; Glycine max; lesion nematode; Medicago sativa; nematode; Pratylenchus scribneri; sorghum; Sorghum bicolor; soybean; sting nematode; Triticum aestivum; vertical distribution; wheat; Zea mays
Yield-loss models were developed for tobacco infected with Meloidogyne incognita grown in microplots under various irrigation regimes. The rate of relative yield loss per initial nematode density (Pi), where relative yield is a proportion of the value of the harvested leaves in uninfected plants with the same irrigation treatment, was greater under conditions of water stress or with high irrigation than at an intermediate level of soil moisture. The maximum rate of plant growth per degree-day (base 10 C) was reduced as nematode Pi increased when plots contained adequate water. When plants were under water stress, increasing Pi did not luther reduce the maximum rate of plant growth (water stress was the limiting factor). Cumulative soil matric potential values were calculated to describe the relationship between available water in the soil (matric potential) due to the irrigation treatments and subsequent plant growth.
Meloidogyne incognita; nematode; Nicotiana tabacum; yield-loss model; soil matric potential; tobacco
The effects of Pratylenchus vulnus on rootstocks of eight commonly used Prunus spp. and one Pyrus communis were evaluated under greenhouse conditions during a 15-month period. In a first experiment, two almonds (Moncayo and Garrigues), one peach (GF-305), and two peach-almond hybrids (GF-677 and Adafuel) inoculated with 2,000 nematodes per plant proved to be good hosts of P. vulnus. Highest (P < 0.05) numbers of nematodes per gram of fresh root weight were recovered from Adafuel and GF-677. Root weights were higher in uninoculated compared to inoculated plants of all rootstocks, whereas top weights of uninoculated Garrigues, GF-305, and GF-677 differed (P < 0.05) from those of inoculated plants. In a second experiment, three plum (Marianna 2624, Myrobalan 605, and San Julian 655-2) and one pear (OHF-333) rootstocks were also found to be good hosts of P. vulnus, although significantly fewer nematodes were recovered from Myrohalan 605 roots than from the other three materials. Inoculated OHF-333 and San Julian 655-2 differed (P < 0.05) in root weights over uninoculated plants. Only inoculated San Julian 655-2 showed differences in top weights over uninoculated treatments. Rootstocks were poor or non-hosts for P. neglectus and P. thornei.
host suitability; nematode; pathogenicity; plant-parasitic nematode; Pratylenchus vulnus; Pratylenchus neglectus; Pratylenchus thornei; Prunus; Pyrus; rootstock
In the first 2 years of a 3-year (1987-89) microplot study, aqueous solutions of oxamyl (32 mg/ml) were applied to cut potato (Solanum tuberosum cv. Russet Burbank) tubers, grown in fine sandy loam infested with Pratylenchus penetrans. The seed-piece treatment alone and the seed-piece treatment followed by three foliar sprays generally reduced (P = 0.05) population densities of P. penetrans in the soil at midseason and in the soil and roots at harvest, compared to the control. In 1989, all seed pieces treated with oxamyl at 96 mg/ml or at 32, 64, and 96 mg/ml followed by a polymer sticker : water (1:4) dip failed to emerge. Only oxamyl at 64 mg/ml reduced (P = 0.05) midseason soil population densities of P. penetrans. A pre-plant soil treatment with 1,3-D reduced (P = 0.05) numbers of P. penetrans at planting each year and increased (P = 0.05) tuber yields in 1988 and 1989 compared to the control. In 1989, tuber yields from the sticker treatment and the oxamyl seed-piece treatment at 64 mg/ml were lower (P = 0.05) than those in the 1,3-D treatment and similar to those from the untreated control, possibly because of phytotoxicity. Oxamyl treatment of potato seed pieces to control P. penetrans does not appear practical for field production.
nematicide; nematode; oxamyl; potato; Pratylenchus penetrans; root-lesion nematode; seed piece; Solanum tuberosum; 1,3-dichloropropene
Populations of three isolates of Bursaphelenchus xylophilus, the pinewood nematode, and one of B. mucronatus were treated with three cryoprotectants at -70 C for 24 hours followed by deep freezing at -180 C in liquid nitrogen for different periods of time. A solution of 15% glycerol, 35% buffer S, and 50% M9, or 1% aqueous solution of dimethylsulfoxide (DMSO), or a mixture of 60% M9 and 40% S buffer were used as cryoprotectants. A significantly larger number of juveniles than adults survived deep freezing. Significantly more nematodes were motile after cryopreservation in the 15% glycerol-S-M9 soludon than in the M9-S buffer solution or the DMSO aqueous solution. When cryopreserved nematodes that had been treated with glycerol solution were plated onto Botrytis cinerea, they reproduced rapidly over several generations. Cryopreserved nematodes were as pathogenic as untreated nematodes to Scots pines.
Bursaphelenchus mucronatus; B. xylophilus; cryopreservation; cryoprotectant; nematode; pinewood nematode; Pinus sylvestris; Scots pine
Gradients of salts of the specific ion repellents for Meloidogyne incognita -- NH₄⁺, K⁺, Cl⁻, and NO₃⁻ -- have been demonstrated to shield tomato roots from infestation in soil. The strategy of these greenhouse experiments was to interpose a salt barrier in a soil column between the plant roots and the nematodes. The relative effectiveness of the salts as a barrier to infective second-stage juveniles in a sandy loam was NH₄NO₃, NH₄Cl > KNO₃ > KCl. Some of these ions are beneficial to plant growth, and the results suggest that a new environmentally tolerable means of plant protection is possible.
ion; Lycopersicon esculentum; Meloidogyne incognita; nematode; protection; repellent
Additional tests of 178 cultivars and lines of soybean against soybean cyst nematode are reported. Cultivars are available with some level of resistance to races 1, 2, 3, 4, 5, 6, 9, and 14, but in some cases the resistance level is moderate. No cultivar or line (except possibly PI 437654) has resistance to all of the races tested. Thirteen cultivars and lines, however, were resistant or moderately resistant to race 1, 14 to race 2, 87 to race 3, 2 to race 4, 3 to race 5, 42 to race 6, 18 to race 9, and 36 to race 14. Some have resistance to more than one race.
Glycine max; Heterodera glycines; nematode; resistance; soybean; soybean cyst nematode
Field experiments were conducted in which the fumigant 1,3-D was applied at broadcast rates of 56 and 112 liters/ha during late winter and spring to two differing soil types in north Florida. No advantage was demonstrated in applying the fumigant at the higher rate for the management of Meloidogyne arenaria on peanut, and there was no disadvantage to applying a standard rate of the fumigant during winter as opposed to the standard practice of a 2-week preplant treatment. At one site, where rainfall was less than adequate for normal peanut yields, all treatments with 1,3-D decreased nematode populations and increased yields 2.5-fold over banded applications of aldicarb (broadcast rates of 6.7 kg/ha at planting with 3.4 kg/ha at peg initiation), and 5-fold over the untreated control. At a site where weather conditions were optimal and soil infestation levels of M. arenariajuveniles were relatively low at harvest, none of the treatments produced peanut yields different (P ≤ 0.05) from the untreated control.
aldicarb; Arachis hypogaea; 1,3-dichloropropene; fumigation; peanut; Meloidogyne arenaria; nematicide; nematode; root-knot nematode
Hemicriconemoides scottolamassesei n. sp., named after Dr. C. Scotto la Massese, from New Caledonia, is described and illustrated. Primary diagnostic characters are females with a continuous head and three lip annules, the first annule being the smallest, stylet length of 65-75 μm, vulva without lateral flaps, and acute tail terminus; J4 has a smooth cuticle without scales or spines; the male has a lateral field with two incisures. Emended measurements, descriptions, illustrations, and new records of distribution are given for H. brachyurus (Loos, 1949) Chitwood &Birchfield, 1957, H. mangiferae Siddiqi, 1961, and H. kanayaensis Nakasono &Ichinoe, 1961. Relationships of H. promissus Vovlas, 1980, based on study of paratypes, and H. intermedius Dasgupta, Raski &Van Gundy, 1969 are discussed; both are proposed as synonyms of H. brachyurus.
Basellina pancheri; distribution; Garcinia sp.; Hemicriconemoides brachyurus; H. intermedius; H. kanayaensis; H. litchi; H. mangiferae; H. promissus; H. scottolamassesei n. sp.; host; nematode; New Caledonia; new species; new synonymy; Psychotria sp.; Rapanea asymetrica; Salacia sp.; synonymy rejection; taxonomy; Weinmannia sp.